Lesson Radian Measure

Lesson Radian Measure

We know that a circle is 360 degrees

How about measuring it in radians

The symbol  Pi

• represented as a decimal is 3.14

• represented as an angle measure = 180 degrees

Radian (PI) measure 

• circle 1 - 90 degress

• circle 2 - 180 degrees

• circle 3 - 270 degrees

• circle 4 - 360 degrees

Slices of PI (PIe)

• If you like Pie than Radian measure is for U!

• Each quadrant is half of the Pi

• Half the circle is one Pi

• The whole circle is then 2 Pi

Fractions of Pi (180 degrees)

Converting degrees to radians

• Going from degrees to Pi

Step 1 - Multiply by Pi Equivalent

• use ratio of Pi over 180 degrees

• Then reduce the fraction to lowest terms

Step 2 - Simplify the fraction (lowest terms)

• You have your answers!

• its that easy

Example 1

Example 2

Finding coterminal angles in radians

Remember we added/subtracted 360 degrees
So now we simply add/subtract 2 Pi

Example - Coterminal Angles